🧫 Bacterial Growth Curve Simulator

About this simulation

When a small inoculum of bacteria is placed in a fresh batch culture — a test tube, a flask, or the petri dish shown here — the population does not grow at a constant rate forever. Plotting cell count against time produces a characteristic S-shaped curve with four named phases: lag, exponential (log), stationary, and death. All four phases fall out of a single logistic growth equation once nutrient depletion and cell death are added.

How it works

• Lag phase — newly inoculated cells synthesize enzymes and adapt to the medium before dividing; colder or hotter conditions lengthen this delay.
• Exponential phase — cells divide at their fastest sustainable rate r, following dN/dt = r·N·(1 − N/K), where K is the carrying capacity set by nutrient supply.
• Stationary phase — growth stalls near K as nutrients run low and waste products accumulate; division roughly balances death.
• Death phase — nutrients are exhausted and toxic byproducts dominate, so the population declines roughly exponentially.

Controls

• Nutrient supply — sets the carrying capacity K: richer medium supports a larger colony and a longer stationary phase.
• Temperature — growth rate peaks near 37°C for this model organism; extreme temperatures slow growth, lengthen lag, and speed up death.
• Simulation speed — how many simulated hours pass per real second.
• ⏸ Pause / ↺ Reset — freeze the clock or start a fresh colony. Drag to rotate the dish, scroll to zoom.

Did you know?

This four-phase curve, first formalized in the early 20th century, still underlies how microbiologists time antibiotic dosing, how food scientists set shelf-life limits, and how bioreactor operators decide exactly when to harvest a culture at its productive peak.